1. Field of the Invention
The present invention relates to apparatus for mixing two or more gas streams and distributing the gas mixture to the input of a reactor, for example, mixing a gaseous hydrocarbon feedstock with an oxygen-containing gas and feeding the mixture to a catalytic reactor for partial oxidation of the feedstock.
2. Description of the Prior Art
Partial oxidation catalytic reactors are useful for reforming hydrocarbons by reacting a gaseous mixture of the hydrocarbon, which may be a hydrocarbon gas or a vaporized liquid hydrocarbon, and an oxidant which may be steam, oxygen, air, or a mixture thereof to form a product including hydrogen, methane, carbon dioxide and carbon monoxide. The product stream can be used as a fuel and/or can be used as a basic feedstock for the production of hydrogen or carbon monoxide or for the synthesis of one or more products such as ammonia, methanol, carbonylated compounds, hydrogenated compounds, etc.
In the mixing and feeding of the gaseous reactants to such reactors, the prior art has long recognized the need for complete mixing of the gaseous reactants as well as the need for preventing flashback of a flame from the reaction chamber into the mixing chamber. Failure to produce complete mixing reduces the quality of the product which then would include excessive completely oxidized components, unoxidized components and free carbon which produces undesirable carbon deposits. Flashback causes similar results and, in addition, can cause heat damage to mixing and distributing equipment.
One prior art technique for eliminating flashback is to interpose a distributor having one or more restricted passageways between the mixing chamber and the reaction chamber. The gas mixture must flow through the restricted passageway or passageways at a velocity exceeding the flashback velocity, i.e., the velocity at which a flame can advance in the combustible mixture from reaction chamber to the mixing chamber. This type of distributor also recognizes the importance of providing a gradual enlarging of the cross-sectional area from the narrow throat or restricted passageway to the entrance of the reaction chamber in order to reduce to a minimum swirling or vortex formation of the flow at the reactor entrance which would promote flashback. In devices having a distributor interposed between a mixing chamber and a reaction chamber, the mixing chamber can contain an explosive mixture and a drop in input or output flows could result in damage.
In one prior art apparatus disclosed in U.S. Pat. No. 3,871,838, there is shown a device for reforming gasoline into a higher octane gaseous fuel wherein a plurality of tubes with a plurality of openings are arranged across the entire cross-section of the flow of vaporized gas for mixing oxygen therewith and for forming narrowed passageways. Baffles formed as part of the walls of the tubes have plane surfaces and gradually enlarge the narrowed passageways in the direction of the reactor. Although this and other prior art devices are disclosed as being suitable for providing increased octane fuel for an automobile combustion engine which burns cleaner and produces less pollution, such apparatus generally is not suitable for large scale hydrocarbon conversion such as may be associated with relatively large scale petroleum refining or synthetic gas-producing installations.